A little over a year ago, I wrote about a Heartland Institute conference in Las Vegas where climate change deniers engaged in a failed attempt to poke holes in the massive body of scientific evidence for human-caused climate change. I quoted Bloomberg News: "Heartland's strategy seemed to be to throw many theories at the wall and see what stuck."

A recent study came to a similar conclusion about contrarian "scientific" efforts to do the same. "Learning from mistakes in climate research," published in Theoretical and Applied Climatology, examined some of the tiny percentage of scientific papers that reject anthropogenic climate change, attempting to replicate their results.

In a Guardian article, co-author Dana Nuccitelli said their study found "no cohesive, consistent alternative theory to human-caused global warming." Instead, "Some blame global warming on the sun, others on orbital cycles of other planets, others on ocean cycles, and so on."

Nuccitelli and fellow researchers Rasmus Benestad, Stephan Lewandowsky, Katharine Hayhoe, Hans Olav Hygen, Rob van Dorland and John Cook note that about 97 per cent of experts worldwide agree on a cohesive, science-based theory of global warming, but those who don't "are all over the map, even contradicting each other. The one thing they seem to have in common is methodological flaws like cherry picking, curve fitting, ignoring inconvenient data, and disregarding known physics."

It's astounding and tragic that, with all the evidence - from volumes of scientific research to the very real effects we are experiencing everywhere - some people stubbornly refuse to believe there's a problem worth addressing. Sadder still: Many of them are political leaders.

Part of the problem is that fossil fuel interests spend enormous amounts of money to sow doubt and confusion, often by funding or setting up organizations like the Heartland Institute in the U.S., the Global Warming Policy Foundation in the U.K., Ethical Oil and Friends of Science in Canada and the International Climate Science Coalition, based in this country but affiliated with similar organizations in Australia and New Zealand and with close ties to Heartland. A number of industry-funded websites also promote fossil fuels at the expense of human life, including Climate Depot and Watts Up With That?

These secretive organizations rarely reveal funding sources, prey on the uninformed and ignorant, and blanket the media with opinion articles, letters to editors and comments, often referring to misleading charts and graphs and bogus "studies" from organizations with names that imply they're scientific when they're anything but. They're assisted by a compliant news media and politicians who also receive fossil fuel industry funding. It's likely the people behind these organizations know they're lying but care more about making money and preserving the lopsided benefits of a polluting sunset industry than finding ways to contribute to human health, well-being and survival.

Those who argue that seven billion people pumping massive amounts of greenhouse gases into the atmosphere aren't having a serious negative impact are out to lunch.

Fortunately, most thinking people don't buy the lies. People from all sectors and walks of life - religious, academic, business, political, activist, social justice and citizenry - are calling for an urgent response to the greatest threat humanity faces. From Pope Francis and the Dalai Lama to Islamic scholars and Hindu, Sikh and Jewish leaders; from Volvo, Ikea and Apple to the International Monetary Fund, World Bank and World Health Organization; from every legitimate scientific academy and institution to enlightened political leaders - all have warned about the serious nature of global warming and the urgent need to do something about it.

Polls and marches, demonstrations and citizen initiatives show that people want action. Yet, despite this tremendous recognition of the reality of our situation, governments have failed to come up with a legally binding, ambitious and universal climate agreement, thanks in part to efforts by countries like Canada, Japan and Australia to stall or water down agreements at economic summits and UN climate conferences.

As world leaders prepare for the December UN climate meeting in Paris, Canadians must impress upon all those who hope to govern us after October 19 the importance of making a positive contribution. As voters, we have the power to make a difference in this critical conversation. Let's exercise it.

Dr. David Suzuki is a scientist, broadcaster, author and co-founder of the David Suzuki Foundation. Written with contributions from David Suzuki Foundation Senior Editor Ian Hanington. Learn more at www.davidsuzuki.org.